为实现高分辨率全天候对地观测，充分利用了长焦距、大孔径空间光学系统的特点，设计了可见、红外共孔径光学系统。系统由可见光光学系统和红外子系统组成，视场角1.3°×0.1°，便于共光路同时推扫成像。可见光光学系统采用同轴三反结构，谱段0.38~0.78 μm，焦距25 m，F 数10，具有中间像面和实际出瞳，便于抑制杂散光。在可见光光学系统出瞳附近分光并以红外子系统与之承接，形成共孔径红外光学系统，谱段8~10.5 μm，焦距4 m，F 数1.6。优化后，双波段像质均接近衍射极限，满足设计指标且全系统结构紧凑。进行了公差分析，并通过蒙特卡罗方法验证了公差分配的结果满足静态传递函数优于0.2的设计要求。

In order to realize the round-the-clock space-to-earth observation with high resolution, a visible and infrared bands common aperture optical system is designed, taking full advantage of the high resolution of the space optical system with long focal length and large aperture. The system consists of a visible spectrum optical system and an infrared (IR) subsystem. The fields of view for the two spectral ranges are both 1.3°×0.1° which is convenient for push-broom imaging simultaneously. A coaxial three-mirror structure with a middle image plane and a real exit pupil to facilitate suppressing the stray light is utilized by the visible spectrum optical system whose working wavelength band is 0.38~0.78 μm, focal length is 25 m, and F-number is 10. The beam is split near the exit pupil of the visible spectrum optical system, to which an IR subsystem is designed and connected. Then the coaxial threemirror optical system and the IR subsystem are integrated into a common aperture IR optical system, whose working wavelength band is 8~10.5 μm, focal length is 4 m and F-number is 1.6. After optimization, the structure of the whole system is compact, and the image quality in the two bands approaches the diffraction limit satisfying the design requirement. The tolerance analysis of the two systems is accomplished, and the result of Monte-Carlo analysis indicates that a static modulation transfer function(MTF) better than 0.2 is achievable.